The present invention is related generally to the field of orthodontics, and more particularly to systems and methods for positioning teeth.
One objective in orthodontics is to move a patient""s teeth to positions where the teeth function optimally and aesthetically. Conventionally, appliances such as braces are applied to the teeth of the patient by an orthodontist. Each appliance exerts continual forces on the teeth and gradually urges the teeth toward their ideal positions. Over a period of time, a treating professional such as an orthodontist adjusts the appliances to move the teeth toward their final destination.
Generally, the orthodontist specifies in a prescription the final tooth arrangement. The prescription is based on the orthodontist""s knowledge and experience in selecting the intended final position of each tooth. The orthodontist or an assistant applies the treatment to move the teeth to their intended destination over a number of office visits. The process of attaching the braces to teeth is tedious and painful to the patient. Additionally, each visit reduces the xe2x80x9cchair-timexe2x80x9d available to the orthodontist that can be made available to another patient.
U.S. Pat. No. 5,975,893 entitled xe2x80x9cMethod and system for incrementally moving teeth,xe2x80x9d issued to Chishti, et al. on Nov. 2, 1999, and assigned to the assignee of the present invention, discloses a system for repositioning teeth with a plurality of individual appliances. The appliances are configured to be placed successively on the patient""s teeth and to incrementally reposition the teeth from an initial tooth arrangement, through a plurality of intermediate tooth arrangements, and to a final tooth arrangement. The system of appliances is usually configured at the outset of treatment so that the patient may progress through treatment without the need to have the treating professional perform each successive step in the procedure.
Additionally, U.S. Pat. No. 6,406,292 filed May 13, 1999, entitled xe2x80x9cSystem and Method for Determining Final Position of Teeth,xe2x80x9d and assigned to the assignee of the present invention, discloses an apparatus and method to define a fit for a set of upper and lower teeth in a masticatory system of a patient by generating a computer representation of the masticatory system of the patient; and determining an occlusion from the computer representation of the masticatory system using one or more keys. U.S. Pat. No. 6,457,972 filed Apr. 20, 2000, assigned to the assignee of the present invention, and entitled xe2x80x9cSystem and Method for Determining Final Position of Teeth,xe2x80x9d shows a system, apparatus and computer-implemented method for arranging a computer model of teeth. According to one implementation, the method includes generating an archform representing an arrangement of teeth; placing a plurality of teeth according to the archform; determining a differential distance between each tooth and its neighbors; and moving each tooth according to the differential distance.
The present invention includes a system, apparatus and computer-implemented method for arranging a computer model of teeth.
In one aspect, a computer-implemented method produces appliances to treat teeth by specifying a sequence of tooth movements to move the teeth through a series of discrete tooth arrangements, wherein at least some of the tooth arrangements are represented by digital data sets; and producing one or more appliances in accordance with the digital data sets wherein the appliances comprise polymeric shells having cavities and wherein the cavities of successive shells have different geometries shaped to receive and resiliently reposition teeth from one tooth arrangement to a successive tooth arrangement.
Implementations of the above aspect may include one or more of the following. A sequence of tooth movements can be specified by moving teeth according to an optimization function, which can include force directed placement, simulated annealing, genetic algorithm, cost minimization, or a random walk algorithm. The sequence of tooth movements can cause the teeth to move until the sum of differential distances for the plurality of teeth exceeds a predetermined threshold, thereby producing a final digital data set. The sequence can include determining a first distance between a selected tooth and a first tooth that is adjacent to the selected tooth; determining a second distance between the selected tooth and a second tooth that is adjacent to the selected tooth; and calculating a difference between the first and second distances. The first and second distances can be the minimum distances between the teeth. The method can include generating an initial final digital data set based on a masticatory system of a patient; generating at least one intermediate digital data set based on the initial digital data set and the final digital data set; and producing an incremental adjustment appliance based on each intermediate digital data set.
The method also includes generating subsequent digital data sets based on prior digital data sets until a final digital data set representing an acceptable tooth arrangement is achieved. Additionally, the method includes generating an initial digital data set representing an initial tooth arrangement; based on the initial digital data set, generating a second data set representing a second tooth arrangement; and, based on the second data set, generating a third data set representing a third tooth arrangement.
In another aspect, an apparatus for producing appliances to treat teeth includes: means for generating a digital arrangement of teeth; means for specifying a sequence of tooth movements to move the teeth to a target arrangement; and means for generating one or more appliances in accordance with the specified sequence of tooth movements, the appliances comprise polymeric shells having cavities and wherein the cavities of successive shells have different geometries shaped to receive and resiliently reposition teeth from one arrangement to a successive arrangement.
In yet another aspect, a computer program product, tangibly stored on a computer-readable medium, for producing appliances to treat teeth, includes instructions operable to cause a programmable processor to: generate a digital arrangement of teeth; specify a sequence of tooth movements to move the teeth to a target arrangement; and generate one or more appliances in accordance with the specified sequence of tooth movements, the appliances comprise polymeric shells having cavities and wherein the cavities of successive shells have different geometries shaped to receive and resiliently reposition teeth from one arrangement to a successive arrangement.
In yet another aspect, a system for treating teeth includes a processor; a display device coupled to the processor; and a data storage device coupled to the processor, the data storage device storing instructions operable to cause the processor to: generate a digital arrangement of teeth; specify a sequence of tooth movements to move the teeth to a target arrangement; and generate one or more appliances in accordance with the specified sequence of tooth movements, the appliances comprise polymeric shells having cavities and wherein the cavities of successive shells have different geometries shaped to receive and resiliently reposition teeth from one arrangement to a successive arrangement.
Advantages of the invention include one or more of the following. When a prescription or other final designation is provided, a computer model can be generated and manipulated to match the prescription. The prescription may be automatically interpreted in order to generate an image as well as a digital data set representing the final tooth arrangement.